Poppet valves are used in a wide variety of applications, such as for controlling the exhausting of a fluid such as a hydraulic oil from cylinders, motors and other working elements. Fluid flow from an inlet port through the poppet valve to an outlet port thereof is typically controlled by controllably moving a poppet of the poppet valve between a first or closed position in sealed relation to a seat and a maximum open or second position displaced from the seat, through a range of partially open positions. Typically, the poppet includes at least one conduit therethrough communicating the inlet port with a control chamber at the back side of the poppet. The fluid pressure in the control chamber exerts a closing force on the poppet holding it against the seat. A spring is also generally used to hold the poppet against the seat when the pressure conditions in the inlet port, control chamber, and an outlet port, are equalized.
Controls for operably controlling the opening of the poppet are well known. Such known controls typically include a control valve operable for allowing fluid flow from the control chamber to another location such as the outlet port of the poppet through a variable regulating or flow control orifice, under control of a pilot fluid signal, a solenoid, or the like. Such known controls further typically have a predetermined maximum area for the flow of the fluid from the control chamber, and the poppet typically includes a metering port operable in cooperation with a metering edge on a sidewall of the valve housing for regulating fluid flow into the control chamber from the conduit through the poppet. To control the movement of the poppet once the fluid flow rate into the control chamber reaches the flow rate from the control chamber, a physical stop is provided, or the poppet is allowed to contact the back wall of the control chamber.
However, it is desirable to eliminate the need for the physical stop. Also, allowing the poppet to contact the back wall of the control chamber can result in the poppet hydraulically locking to the back face of the chamber, causing control and operational problems when the control signal is diminished and the poppet is required to move to a lower flow rate position. Additionally, in some instances it is desirable to provide stop means for the poppet at an intermediate location, which is difficult to achieve using a physical stop.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.